Expose connection subtype from NetworkChangeNotifier

net/base/network_change_notifier.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 #define NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 252 matching lines @@
   // threads try to access the API below, and it must outlive all other threads
   // which might try to use it.
   static NetworkChangeNotifier* Create();
 
   // Returns the connection type.
   // A return value of |CONNECTION_NONE| is a pretty strong indicator that the
   // user won't be able to connect to remote sites. However, another return
   // value doesn't imply that the user will be able to connect to remote sites;
   // even if some link is up, it is uncertain whether a particular connection
   // attempt to a particular remote site will be successful.
-  // The returned value only describes the connection currently used by the
-  // device, and does not take into account other machines on the network. For
-  // example, if the device is connected using Wifi to a 3G gateway to access
-  // the internet, the connection type is CONNECTION_WIFI.
+  // The returned value only describes the first-hop connection, for example if
+  // the device is connected via WiFi to a 4G hotspot, the returned value will
+  // be CONNECTION_WIFI, not CONNECTION_4G.
   static ConnectionType GetConnectionType();
 
+  // Returns the device's current default active network connection's subtype.
+  // The returned value only describes the first-hop connection, for example if
+  // the device is connected via WiFi to a 4G hotspot, the returned value will
+  // reflect WiFi, not 4G. This method may return SUBTYPE_UNKNOWN even if the
+  // connection type is known.
+  static ConnectionSubtype GetConnectionSubtype();
+
   // Sets |max_bandwidth_mbps| to a theoretical upper limit on download
   // bandwidth, potentially based on underlying connection type, signal
   // strength, or some other signal. If the network subtype is unknown then
   // |max_bandwidth_mbps| is set to +Infinity and if there is no network
   // connection then it is set to 0.0. The circumstances in which a more
   // specific value is given are: when an Android device is connected to a
   // cellular or WiFi network, and when a ChromeOS device is connected to a
   // cellular network. See the NetInfo spec for the mapping of
   // specific subtypes to bandwidth values: http://w3c.github.io/netinfo/.
   // |connection_type| is set to the current active default network's connection
@@ skipping 202 matching lines @@
   // TODO(szym): Retrieve AddressMap from NetworkState. http://crbug.com/144212
   virtual const internal::AddressTrackerLinux*
       GetAddressTrackerInternal() const;
 #endif
 
   // These are the actual implementations of the static queryable APIs.
   // See the description of the corresponding functions named without "Current".
   // Implementations must be thread-safe. Implementations must also be
   // cheap as they are called often.
   virtual ConnectionType GetCurrentConnectionType() const = 0;
+  virtual ConnectionSubtype GetCurrentConnectionSubtype() const;
   virtual void GetCurrentMaxBandwidthAndConnectionType(
       double* max_bandwidth_mbps,
       ConnectionType* connection_type) const;
   virtual bool AreNetworkHandlesCurrentlySupported() const;
   virtual void GetCurrentConnectedNetworks(NetworkList* network_list) const;
   virtual ConnectionType GetCurrentNetworkConnectionType(
       NetworkHandle network) const;
   virtual NetworkHandle GetCurrentDefaultNetwork() const;
 
   // Hook that allows derived implementations to log histograms at the time a
@@ skipping 62 matching lines @@
 
   // Set true to disable non-test notifications (to prevent flakes in tests).
   static bool test_notifications_only_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_H_